Predictable bonding of adhesive indirect restorations: factors for success

Effect of Dentin Contamination with Hemostatic Agents and Cleaning Techniques on Bonding with Self-Adhesive Resin Cement

BACKGROUND Dentin contamination with hemostatic agents before bonding indirect restorations negatively affects the bond strength. However, the consensus on which materials could be used to clean contamination of hemostatic agents has not been explored. The aim of this study was to assess the effect of Katana Cleaner applied on the surface of dentin contaminated with hemostatic agents on the shear bond strength (SBS) of self-adhesive resin cement by comparing it with three other surface cleaners. MATERIAL AND METHODS Ninety dentin specimens were divided into a no contamination group (control) (n=10), 4 groups contaminated with 25% aluminum chloride (Viscostat Clear) (n=40), and 4 groups contaminated with 20% ferric sulfate (Viscostat) (n=40). Subsequently, 4 different cleaners were used for each contamination group (water rinse, phosphoric acid, chlorhexidine, and Katana Cleaner). Then, self-adhesive resin cement was directly bonded to the treated surfaces. All specimens were subjected to 5000 thermal cycles of artificial aging. The shear bond strength was measured using a universal testing machine. RESULTS Two-way analysis of variance showed that the contaminant type as the main factor was statistically non-significant (p=0.655), cleaner type as the main factor was highly significant (p<0.001), and interaction between the contaminant and cleaner was non-significant (p=0.51). The cleaner type was the main factor influencing the bond strength. Phosphoric acid and chlorhexidine showed better performance than Katana Cleaner. CONCLUSIONS Cleaning dentin surface contamination with phosphoric acid and chlorhexidine had better performance than with Katana Cleaner.

Effect of dentin surface conditions and curing mode of resin cement on the dentin bond strength

This study investigates the effects of dentin's drying time, roughness, and curing modes of resin cement on bond strength. Forty human teeth were divided into eight groups based on three experimental factors: dentin's roughness by 240-or 600-grit SiC paper (coarse or fine), dentin wetness with air-drying time (5-s or 10-s), and Single Bond Universal adhesive's curing mode by co-curing with RelyX Ultimate cement or light-curing separately (co-curing or light-curing). The micro-tensile bond strength of fifteen resin-dentin stikcs per groups was measured. Failure mode and adhesive layers were observed using stereoscopic and confocal laser scanning microscopy, respectively. The curing mode of the adhesive layer affected the bond strength of the dentin-resin cement (p<0.05). In particular, the light-curing mode exhibited a significantly higher bond strength than the co-curing one (p<0.05). The bond strength between the resin cement and dentin was improved in the 5-s drying groups than in the 10-s drying groups.

Impact of try-in paste removal on the fatigue behavior of bonded lithium disilicate ceramics

This in vitro study assessed the effectiveness of three cleaning protocols (air-water spray, 37% phosphoric acid, or Ivoclean) on lithium disilicate restorations' fatigue behavior after try-in paste application, compared to a clean condition. Lithium disilicate discs (IPS e.max CAD, Ivoclar) with Ø-= 12 mm and 1 mm thickness were prepared from prefabricated CAD-CAM blocks, polished, subjected to CAD-CAM milling topography simulation and crystallization. After, etching with 5% hydrofluoric acid and the application of try-in paste (Variolink try-in paste shade white; load of 2.5 N for 5 min) was performed. Discs that received try-in paste were divided into three groups according to the removal protocol: SPRAY - air-water spray for 30 s; HPO - active application of 37% phosphoric acid for 60 s; IVOC - application of Ivoclean for 20 s. Control group (CTRL group) did not receive the try-in paste application. Half of the specimens (n= 15) were tested in the baseline condition (24 h up to 7 days), and the others underwent 25,000 thermal cycles (5 - 55 °C) + 210 days of distilled water storage (37 °C). Additional specimens (n= 3) underwent monotonic testing (1 mm/min). Fatigue testing involved a cyclic fatigue approach (20 Hz, initial load = 100 N - 5000 cycles, step size = 50 N - 10,000 cycles) until a visible crack appeared. Fractographic and topographic analyses were performed. Fatigue data were statistically analyzed with two-way ANOVA, Kaplan-Meier log-rank (Mantel-Cox), and independent t-test (α= 0.05). In the baseline condition, the IVOC group resulted in a superior fatigue behavior compared to the CTRL and SPRAY groups, but similar to the HPO group. The HPO and SPRAY presented a similar fatigue behavior to the CTRL group. It was noticed a decrease in fatigue behavior after aging, which resulted in all the cleaning protocols leading to similar fatigue behavior compared to the CTRL group. On the SPRAY group surface, try-in pastes remnants were noticed. In summary, despite a detrimental impact at baseline conditions, all tested cleaning protocols seem proper to remove the try-in paste from the ceramic's surface in the long-term evaluation.

Current trends in placing posterior composite restorations: Perspectives from Palestinian general dentists: A questionnair study

Aim

The success of composite restorations relies on material selection and practitioner-related factors that shape the overall outcome. This study explores the practices of Palestinian general dental practitioners in placing posterior composites, examining the impact of work sector, experience, and gender on their choices.

Materials and Methods

The study was conducted as an online cross-sectional questionnaire and involved 351 participants, with a response rate of 69.8%. The survey comprised 18 closed-ended questions covering demographics, material selection, and composite placement in special cases, techniques, and factors influencing the choices. Statistical analyses included descriptive statistics, chi-squared tests, and Fisher's exact tests.

Results

Composite was the predominant choice for small-size (83.7%) and large-size posterior cavities (60.4%). Practitioners commonly opted for composite restorations in cases involving occlusal parafunctional activity (60%), poor oral hygiene (78%), and subgingival cavities (72.2%). Only 19.6% and 5.3% reported occlusal and gingival beveling, respectively. Rubber dams for isolation stood at 30%, one-step self-etch adhesives at 44.9%, and the oblique layering technique at 51%. Light-emitting diode curing units were popular (97.55%), but monitoring output with a radiometer was infrequent (93.5%). Tofflemire metal matrix usage was 46.1%, whereas a sectional matrix system was employed by 29.8%. A 2 mm layer exposure to light curing for 20 s was reported by 62%, and 27.75% utilized additional light-curing postmatrix band removal.

Conclusion

The study highlights the need for Palestinian dental professionals to update their clinical approaches in placing composite restorations in posterior teeth. Gender, work sector, and experience influence practitioners' choices, emphasizing the importance of tailored continuing education programs for improving clinical practices.

The natural CAD/CAM anterior implant single tooth restoration: A novel digital workflow

OBJECTIVE

To report a novel digital workflow to replace an anterior maxillary tooth lost due to trauma with an implant multilayer restoration by using the patient's extracted tooth as a final crown restoration using computer-aided design/computer-aided manufacturing (CAD/CAM) technology.

CLINICAL CONSIDERATIONS

Instead of using the patient's natural tooth as an immediate provisional restoration to achieve predictable results in terms of esthetics and soft tissue structure, a novel digital strategy was performed to obtain a natural final crown restoration by using the patient's tooth associated with a lithium disilicate customized implant abutment.

CONCLUSIONS

The perspective of using this strategic approach for implant restorative dental treatments in patients with traumatic root fractures in the anterior region has great potential as it helps to maintain the emergence profile of the natural dentition and esthetics.

CLINICAL SIGNIFICANCE

Optimal esthetic outcomes are challenging in implant dentistry regarding soft tissue structure and morphology factors. Using natural teeth from surgery to deliver the final restoration might be beneficial when an anterior tooth is lost due to trauma.

The Classification and Selection of Adhesive Agents; an Overview for the General Dentist

Adhesive agents are essential to most restorative procedures used in everyday practice. Depending on the clinical situation, the dentist will choose among a rapidly evolving variety of adhesive agents (bonding agents). Due to the availability of many adhesive agents, appropriate selection can take time and effort. Typically, a practitioner relies more on marketing and experience than in-depth material knowledge. The classification of adhesive agents may need to be clarified and easier to remember due to its lack of relevance to clinical procedures. This paper reviews the published literature retrieved from PubMed, Google Scholar, and Scopus by using specific keywords "adhesive agents", "classification", "dentin", "enamel", "universal", "self-etch", "etch-and-rinse", and "bonding". The titles and abstracts were screened, and the relevant literature was retrieved. The list of references from each identified article was examined to find other potentially relevant articles. Adhesive agents can be classified as etch-and-rinse, self-etch, or "multi-mode" according to their approach to interacting with the smear layer, and each approach can be further classified according to the number of clinical steps required during application. This article reviews the classification of current adhesive agents and discusses the properties that make a specific adhesive agent the optimal choice for a particular clinical indication. The review will assist the general dentist in understanding the various types of available adhesive agents and how they function. Overall, the review will facilitate decision-making and allow the selection of appropriate materials.

Effect of different surface treatments on resin-matrix CAD/CAM ceramics bonding to dentin: in vitro study

BACKGROUND

Evaluating the effect of different surface treatment methods on the micro-tensile bond strength (µTBS) of two different resin-matrix computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics (RMCs).

METHODS

A standardized inlay preparations were performed on 100 intact maxillary premolars. According to the type of the restorative material, the teeth were randomly divided into two equally sized groups (n = 50): (polymer-infiltrated ceramic (Vita Enamic) and resin-based composites (Lava Ultimate)). The inlays were fabricated using CAD/CAM technology. In each group, the specimens were randomly assigned to five subgroups (n = 10) according to the surface treatment method: group 1 used was the control group (no surface treatment); group 2, was treated with air abrasion with 50 μm Al2O3 (A) and universal adhesive (UA); group 3, was treated with air abrasion with 50 μm Al2O3 (A) and silane coupling agent (S); group 4, was treated with hydrofluoric acid (HF) and universal adhesive (UA) and group 5, was treated with Hydrofluoric acid (HF) + silane coupling agent (S). The inlays were then cemented to their respective preparations using dual-cure self-adhesive resin cement (RelyX U200, 3 M ESPE) according to the manufacturer's instructions. The µTBS test was conducted in all groups, and stereomicroscope and scanning electron microscope were used to inspect the failure mode. The data were statistically analyzed using a two-way analysis of variance (ANOVA) and Tukey's post-hoc multiple comparison tests at a significance level of p < 0.05.

RESULTS

Surface treatments significantly increased the µTBS of the materials compared to the control group (p < 0.05). For CAD/CAM RBCs, the µTBS value highest in group 2 whereas, for PICN, the µTBS value was highest in group 3. Cohesive failure of CAD/CAM restorative material was the most predominant mode of failure in all treated groups, whereas adhesive failure at restoration-cement interface was the most predominant failure mode in the control group.

CONCLUSION

Surface treatments increase the µTBS of resin-matrix CAD/CAM ceramics to tooth structure. Air abrasion followed by universal adhesive and hydrofluoric acid followed by silane application appears to be the best strategies for optimizing the bond strength of CAD/CAM RBCs and PICN respectively.

Influence of Air-Barrier and Curing Light Distance on Conversion and Micro-Hardness of Dental Polymeric Materials

This study aims to assess the conversion degree and hardness behavior of two new commercial dental restorative composites that have been submitted to light curing in different environments (air and glycerin, respectively) at various distances from the light source (1 to 5 mm) and to better understand the influence of the preparation conditions of the restorative materials. Through FT-IR spectrometry, the crosslinking degree of the commercial restorative materials have been investigated and different conversion values were obtained (from ~17% to ~90%) but more importantly, it was shown that the polymerization environment exhibits a significant influence on the crosslinking degree of the resin-based composites especially for obtaining degrees of higher polymerization. Additionally, the mechanical properties of the restorative materials were studied using the nanoindentation technique showing that the nano-hardness behavior is strongly influenced not only by the polymerization lamp position, but also by the chemical structure of the materials and polymerization conditions. Thus, the nanoindentation results showed that the highest nano-hardness values (~0.86 GPa) were obtained in the case of the flowable C3 composite that contains BisEMA and UDMA as a polymerizable organic matrix when crosslinked at 1 mm distance from the curing lamp using glycerin as an oxygen-inhibitor layer.

Matrix transfer techniques for direct paste composite resins

This article discusses potential concerns and important considerations when selecting and using matrix transfer techniques for the direct, definitive addition of composite resin to teeth. It also provides guidance to aid these processes with the use of case studies, primarily focusing on the management of tooth wear.

Considers the advantages and disadvantages of using different matrix transfer techniques for the restoration of multiple teeth with direct paste composite.

Addresses common concerns and problems associated with using matrix transfer techniques, particularly in relation to managing the worn dentition.

Suggests guidance on selecting appropriate matrix transfer techniques to minimise complications and optimise outcomes through the exploration of case studies.

Longevity of gold restorations in posterior teeth: A retrospective study up to 10-years

OBJECTIVE

In this retrospective clinical study, we investigated the long-term survival and success of indirect gold restorations, placed by undergraduate students.

MATERIAL AND METHODS

The study included 72 gold restorations in 45 patients, placed in a five-year period between 2009 and 2013. Two experienced dentists performed the evaluation following the FDI criteria after 5 to 10 years. Kaplan-Meier test was used for longevity analysis of success and survival. Data were tested for normality with Shapiro-Wilk test. Cox regression analysis, with significance level appointed at p ≤ .05, was performed using success and survival of restorations as dependent variables. Annual failure rates (AFRs) were calculated.

RESULTS

Overall, 72 indirect gold restorations prepared in posterior teeth were assessed, with an observation time from 63 months to 117 months. The mean service time was 88.1 months and the median 87 months. No failures, but 2 repairs, were observed during the first five years. From 5 to 10 years 1 replacement and 1 more repair occurred. The survival and success rates of gold restorations were calculated at 9 years with 98.6% and 91%, respectively. Restorations placed on premolars had higher survival and success rates compared to molars. Three cases were categorized as repairs: in two cases, a root canal treatment was needed and, in one other, an occlusal perforation of the restoration was observed.

CONCLUSIONS

Posterior indirect gold restorations placed by dental undergraduate students showed a highly predictable clinical performance in terms of success and survival. These results are comparable with survival rates reported in literature for restorations cemented in general dental practices.

CLINICAL SIGNIFICANCE

Casted gold restorations placed from dental students in an undergraduate setting show high survival rates, similar to professional dentists.

Minimally Invasive Rehabilitation of Posterior Erosive Tooth Wear: Two Case Reports of the One-Stage Dahl Approach

Rehabilitation of posterior erosive tooth wear can be especially challenging in the presence of substantial tooth structure loss and limited inter-occlusal space. This article describes two case reports illustrating a conservative approach using the one-step Dahl approach in the management of localized posterior erosive tooth wear. The occlusal surfaces of worn teeth in both cases were successfully restored using direct composite resin and gold onlay, respectively. The material was placed in supra-occlusion during the initial stage. This technique enables intrusion of affected worn teeth and the opposing counterpart. Eruption of the remaining dentition will occur after two to three months to re-establish a complete occlusal relationship. With proper treatment planning, the one-step Dahl approach offers a simpler and predictable positive outcome in restoring structurally compromised posterior worn teeth.